Swift Trigger: 1037828;

Presumed name: GRB 210321A

BAT	05^h 51^m 29.76^s, +70° 07′ 08.4″
position:	(87.874, +70.119 ± 180″)
XRT	05^h 51^m 35.10^s, +70° 07′ 49.5″
position:	(87.89627, 70.13042 ± 3.7″)
UVOT	05^h 51^m 34.73^s, +70° 07′ 49.8″
position:	(87.8947, +70.1305 ± 0.6″)
Galactic N_HI:	8.05×10⁰ cm^-2
Galactic E(B-V):	0.111 mag

Best RA:	05^h 51^m 34.73^s	= 87.8947 d
Best Dec:	+70° 07′ 49.8″	= +70.1305 d

Gal Lat:	20.53
Gal Long:	143.46

Sun angle:	88.87°, -5.8 hr East of Sun

¹Sper #3 auto processing.

Galaxies within 3.33 of XRT position

	RA*	Dec*		Catalogue
12.1	87.8846	70.1308		NED
26.8	87.8758	70.1269		NED
28.4	87.9112	70.1250		NED
32.0	87.9204	70.1322		NED
33.2	87.8700	70.1344		NED
38.5	87.8729	70.1228		NED
38.9	87.8954	70.1414		NED
40.3	87.9087	70.1203		NED
40.3	87.8762	70.1397		NED
42.5	87.9287	70.1283		NED
46.2	87.8662	70.1219		NED
48.1	87.8554	70.1300		NED
48.2	87.8592	70.1247		NED
55.7	87.9290	70.1197	B=21.7, R=19.3	APM-N
57.2	87.8750	70.1450		NED
58.1	87.9287	70.1192		NED
59.2	87.9129	70.1458	B1=19.5, B2=18.9, I=18.3, R1=18.8, R2=18.4	USNO-B1
59.3	87.8588	70.1417		NED
59.9	87.9125	70.1461		NED
60.3	87.8819	70.1144	B=19.6, R=18.1	APM-N
60.3	87.8821	70.1144		NED
62.8	87.9392	70.1219		NED
63.8	87.8425	70.1311		NED
64.3	87.8958	70.1125		NED
64.4	87.8562	70.1183		NED
65.9	87.8425	70.1308	B=21.3, R=19.9	APM-N
67.4	87.9496	70.1306		NED
68.8	87.9442	70.1394		NED
72.7	87.8362	70.1269		NED
73.0	87.8525	70.1447		NED
73.3	87.8432	70.1210	B=21.7, R=20.0	APM-N
76.0	87.8525	70.1150		NED
76.6	87.8758	70.1103		NED
76.7	87.8413	70.1417		NED
79.6	87.9025	70.1084	B=17.1, R=15.9	APM-N
79.8	87.9429	70.1156		NED
80.5	87.8337	70.1389		NED
80.5	87.9042	70.1083		NED
81.2	87.9108	70.1086		NED
82.0	87.8329	70.1217		NED
82.8	87.8883	70.1533		NED
82.9	87.8549	70.1487	B=21.8, R=20.0	APM-N
83.3	87.8325	70.1211		NED
83.8	87.8996	70.1072		NED
87.0	87.8883	70.1544		NED
87.2	87.8237	70.1286		NED
87.5	87.8725	70.1536		NED
87.7	87.8717	70.1536		NED
87.8	87.8250	70.1244		NED
89.5	87.9513	70.1147		NED
92.4	87.9021	70.1561		NED
93.2	87.9625	70.1189		NED
93.5	87.8242	70.1406		NED
94.8	87.8392	70.1122		NED
95.6	87.9613	70.1444		NED
99.0	87.9750	70.1278		NED
99.4	87.8229	70.1175		NED
100.9	87.9762	70.1347		NED
102.2	87.8129	70.1247		NED
103.0	87.8233	70.1153		NED
104.1	87.8333	70.1506		NED
104.5	87.8675	70.1581		NED
105.7	87.9146	70.1592		NED
107.9	87.8799	70.1599	B=21.9, R=19.9	APM-N
108.2	87.8566	70.1573	B=21.9, R=19.3	APM-N
108.2	87.9821	70.1264		NED
110.4	87.8337	70.1531		NED
110.6	87.8467	70.1567		NED
111.3	87.8129	70.1169		NED
112.5	87.9279	70.1597		NED
113.0	87.9312	70.1017		NED
113.5	87.8046	70.1228		NED
114.4	87.8067	70.1414		NED
114.4	87.8029	70.1367		NED
114.8	87.9519	70.1561	B=21.8, R=20.0	APM-N
115.3	87.8237	70.1094		NED
115.5	87.8244	70.1096	I=18.9, R2=19.9	USNO-B1
116.2	87.7996	70.1294		NED
116.3	87.8190	70.1493	B1=21.0, I=18.3	USNO-B1
117.0	87.8171	70.1494		NED
118.4	87.8571	70.1004	B=21.7, R=20.0	APM-N
119.9	87.9121	70.0978		NED
120.1	87.8367	70.1036		NED
126.8	87.8133	70.1086		NED
130.9	87.7992	70.1469		NED
132.0	87.8325	70.1606		NED
133.3	88.0029	70.1344		NED
134.7	87.9825	70.1531		NED
135.8	87.9858	70.1089		NED
136.2	87.9721	70.1033		NED
136.3	87.8504	70.1653		NED
136.6	87.8042	70.1083		NED
136.8	87.9493	70.1639	B1=21.0, B2=21.4	USNO-B1
137.2	87.9792	70.1056		NED
137.7	87.9500	70.1640	B=21.2, R=20.0	APM-N
137.9	87.9146	70.0928		NED
138.7	87.9408	70.1656		NED
138.8	87.9954	70.1128		NED
139.0	88.0083	70.1303		NED
140.0	87.7804	70.1278		NED
140.6	88.0028	70.1158	B2=21.9, R2=19.2	USNO-B1
141.7	87.8232	70.1610	B2=20.9, I=18.6, R2=19.2	USNO-B1
142.4	87.7963	70.1517		NED
142.9	87.7900	70.1128		NED
143.3	87.7808	70.1400		NED
143.5	87.7907	70.1131	B2=21.5, I=18.8, R2=19.4	USNO-B1
144.2	87.7771	70.1339		NED
144.8	87.9033	70.1706		NED
145.0	87.8863	70.1706		NED
145.4	87.9036	70.1707	B=21.5, R=19.4	APM-N
145.4	87.9048	70.1707	B1=20.8, I=18.9	USNO-B1
145.6	87.8367	70.1658		NED
146.8	87.8037	70.1039		NED
147.0	87.8976	70.0896	B=21.7, R=18.9	APM-N
147.4	87.8017	70.1564		NED
147.8	87.8812	70.0897		NED
148.0	87.7842	70.1472		NED
148.1	87.8979	70.0894		NED
149.0	88.0084	70.1143	B=21.2, R=18.6	APM-N
149.3	87.8500	70.1692		NED
149.9	87.8304	70.0950		NED
151.0	87.8200	70.0972		NED
153.2	87.8733	70.1725		NED
153.2	87.7696	70.1303		NED
153.5	87.8627	70.0893	B=21.1, R=19.5	APM-N
154.9	87.8421	70.0914		NED
155.8	88.0079	70.1108		NED
156.2	88.0175	70.1425		NED
156.9	87.9492	70.0907	B=20.0, R=18.2	APM-N
157.3	88.0021	70.1064		NED
157.7	87.8254	70.1675		NED
158.1	87.9492	70.0906		NED
158.6	87.8912	70.1744		NED
159.5	87.9954	70.1586		NED
160.1	88.0253	70.1230	B1=20.8, B2=21.4	USNO-B1
160.5	87.9679	70.0931	B=21.9, R=20.0	APM-N
160.9	87.8004	70.0994		NED
161.6	87.7654	70.1208		NED
161.8	87.9079	70.0858		NED
162.2	87.8546	70.1733		NED
162.4	87.9059	70.1754	B=21.8, R=20.0	APM-N
163.0	87.7800	70.1075		NED
163.6	87.8741	70.1752	B2=21.0, R2=20.5	USNO-B1
165.3	88.0288	70.1256		NED
165.5	87.8304	70.0900		NED
166.0	88.0006	70.1010	B=21.9, R=20.0	APM-N
166.0	87.9996	70.1014		NED
166.5	88.0116	70.1550	B2=20.5, I=18.4, R2=20.0	USNO-B1
167.3	87.8033	70.0958		NED
167.3	87.9737	70.0928		NED
167.4	88.0108	70.1550		NED
167.6	87.8889	70.0839	B=21.6, R=20.0	APM-N
167.9	87.8229	70.0908		NED
168.1	87.9871	70.0961		NED
168.4	88.0062	70.1581		NED
169.3	87.8220	70.0907	B1=16.9, B2=16.5, I=15.6, R1=15.6, R2=15.7	USNO-B1
170.5	87.7917	70.1625		NED
170.6	88.0122	70.1568	B2=20.8, R1=19.1	USNO-B1
170.6	87.7558	70.1253		NED
171.2	87.9671	70.1711		NED
171.3	87.7546	70.1308		NED
172.0	87.7671	70.1103		NED
172.3	88.0204	70.1519		NED
172.4	87.7916	70.1625	B1=14.8, B2=14.3, I=13.8, R1=13.7, R2=13.6	USNO-B1
172.6	87.9204	70.1775		NED
173.3	87.7717	70.1544		NED
173.4	87.8308	70.1736		NED
173.6	87.7674	70.1103	I=18.6, R2=20.0	USNO-B1
173.8	87.9958	70.0967		NED
174.6	87.9154	70.1785	B=20.8, R=18.5	APM-N
174.6	87.9155	70.1785	B1=20.8, B2=20.7, I=17.6, R1=18.9, R2=18.9	USNO-B1
174.8	87.9154	70.1786		NED
175.4	87.8698	70.1783	B2=21.7, I=18.6, R2=19.5	USNO-B1
175.9	87.8717	70.1786	B=21.9, R=19.6	APM-N
175.9	87.8723	70.1786	I=18.6, R2=19.6	USNO-B1
176.5	88.0383	70.1356		NED
176.7	88.0146	70.1023	B1=19.8, B2=18.8, I=16.6, R1=17.2, R2=17.4	USNO-B1
177.0	87.8996	70.1797		NED
177.3	87.7645	70.1100	B1=21.0, I=16.6	USNO-B1
177.3	87.8621	70.1786		NED
177.4	87.9887	70.1681		NED
178.5	88.0344	70.1464	B=21.6, R=20.0	APM-N
178.7	88.0146	70.1022		NED
179.3	88.0296	70.1500		NED
180.3	87.8283	70.0858		NED
181.1	87.8246	70.1747		NED
181.2	87.8104	70.1719		NED
181.4	88.0379	70.1178		NED
181.6	87.8742	70.0806		NED
182.2	88.0433	70.1272		NED
182.3	87.7496	70.1419		NED
182.3	87.7487	70.1203		NED
183.1	87.8746	70.1808		NED
183.2	87.8942	70.0797		NED
185.4	87.9796	70.0878		NED
186.2	87.9531	70.0824	B=21.8, R=20.0	APM-N
186.4	87.7429	70.1258		NED
187.6	88.0154	70.0986		NED
187.7	88.0283	70.1561		NED
187.8	87.7496	70.1478		NED
187.9	87.7483	70.1144		NED
188.0	87.8133	70.0861		NED
188.3	87.7671	70.1600		NED
189.1	87.8425	70.0811		NED
189.2	87.8869	70.1829	B=21.8, R=20.0	APM-N
190.4	87.9774	70.0853	B=21.9, R=20.0	APM-N
191.2	87.9746	70.0850		NED
194.3	87.7584	70.1573	B=21.6, R=20.0	APM-N
194.7	87.9679	70.0825		NED
194.9	87.8425	70.1817		NED
195.7	87.9579	70.0806		NED
195.7	87.7346	70.1317		NED
195.8	88.0508	70.1189		NED
196.6	88.0050	70.0908		NED
196.6	87.7504	70.1064		NED
197.2	87.7667	70.0972		NED
198.0	87.8831	70.0756	B=20.1, R=17.4	APM-N
198.5	87.8829	70.0756		NED
198.7	87.9217	70.1850		NED
198.7	87.8537	70.1839		NED
199.1	88.0267	70.0981		NED
199.1	87.7521	70.1575		NED
199.9	88.0354	70.1586		NED

Queried APM-N, SDSS, PSCz, SSS, NED, 2MASSX, USNO-B1.

* RA/Dec in equinox J2000

Magnitudes depend on the catalogue. e.g. For Sloan, R is the Sloan r mag, not the Johnson R from APM, for example